Showing papers in "Ferroelectrics in 2006"
TL;DR: In this paper, a morphotropic phase boundary (MPB) between orthorhombic and tetragonal has been developed, which exhibits a piezoelectric actuator constant d 33 of 230 pm/V, 2.34 times that of pure (K 0.5 Na0.5 )NbO 3 (KNN).
Abstract: A new solid solution system, namely {(K 0.5 Na 0.5 ) 1− x Li x }(Nb 1− y Ta y )O 3 , with full density, a large piezoelectric constant and high stability has been developed. The system has a morphotropic phase boundary (MPB) between orthorhombic and tetragonal. The MPB gives the largest piezoelectric d constant at {(K 0.5 Na 0.5 ) 0.97 Li 0.03 }(Nb 0.8 Ta 0.2 )O 3 , which exhibits a piezoelectric actuator constant d 33 of 230 pm/V, 2.34 times that of pure (K 0.5 Na 0.5 )NbO 3 (KNN). Also, it gives a piezoelectric coupling Kp value (0.505), a dielectric constant (1256), and an elastic compliance (10.9 TPa−1 ) 1.51, 2.93, and 1.14 times those of pure KNN, respectively. The long-term stability of the dielectric loss was demonstrated to be far superior to that of pure KNN.
190 citations
TL;DR: A comparison of compressive properties of syntactic foams having microballoons of four different wall thicknesses in five volume fraction each is presented in this paper, where the compressive strength and modulus vary linearly with respect to the foam density.
Abstract: The density of hollow particle (microballoon) filled composites called syntactic foams can be varied by two methods. The first method is the variation in microballoon volume fraction and the second method is the variation in the microballoon wall thickness, while keeping their volume fraction the same. A comparison of compressive properties of syntactic foams having microballoons of four different wall thicknesses in five volume fraction each is presented here. It is found that the compressive strength and modulus vary linearly with respect to the foam density. Dielectric constant, dielectric loss and electrical impedance are measured for four syntactic foam compositions with respect to temperature and frequency. Dielectric constant and loss are found to decrease with increase in frequency and with decrease in temperature in the range of 40–140°C.
75 citations
TL;DR: In this paper, the authors discuss various stability aspects related to the piezoelectric properties of polypropylene ferroelectrets, including the permanent trapping of electric charges inside the polymer voids.
Abstract: Ferroelectrets are thin films of polymer foams, exhibiting piezoelectric properties after electrical charging. Ferroelectret foams usually consist of a cellular polymer structure filled with air. Polymer-air composites are elastically soft due to their high air content as well as due to the size and shape of the polymer walls. Their elastically soft composite structure is one essential key for the working principle of ferroelectrets, besides the permanent trapping of electric charges inside the polymer voids. The elastic properties allow large deformations of the electrically charged voids. However, the composite structure can also possibly limit the stability and consequently the range of applications because of, e. g., penetration of gas and liquids accompanied by discharge phenomena or because of a mechanical pre-load which may be required during the application. Here, we discuss various stability aspects related to the piezoelectric properties of polypropylene ferroelectrets. Near and below room tempe...
70 citations
TL;DR: It has been proved that the domain growth acceleration after merging is due to formation of super-fast X-oriented walls and degree of deviation of the switching conditions from equilibrium characterized by ratio between switching and screening rates.
Abstract: The main aspects of domain engineering in LiNbO 3 and LiTaO 3 representing field induced formation of the tailored domains are discussed. The special attention is paid to sideways domain wall motion. Experimentally observed wall motion scenarios have been classified. It is discovered that the realization of the given scenario is defined by degree of deviation of the switching conditions from equilibrium characterized by ratio between switching and screening rates. It has been proved that the domain growth acceleration after merging is due to formation of super-fast X-oriented walls. The loss of wall shape stability and formation of nano-domains have been considered.
68 citations
TL;DR: In this paper, a 2-phase model was used to estimate the piezoelectric properties from the domain wall of the multidomain BaTiO 3 single crystals.
Abstract: For the [111] poled barium titanate (BaTiO 3 ) single crystals with the engineered domain configuration, it was clearly observed that the piezoelectric properties increased with decreasing domain sizes. To explain the phenomenon, the multidomain single crystals were regarded as the composite of (a) a distorted domain wall region and (b) a normal tetragonal domain region. Using a 2-phases model, the piezoelectric properties from the domain wall were estimated. As a result, ultrahigh piezoelectric constants over 8,000 pC/N were expected from the domain wall region. Moreover, this study suggested that it is possible to obtain the lead-free piezoelectric materials with the d 31 and d 33 over 1,000 pC/N, when the domain sizes can decrease below 1 μ m.
55 citations
TL;DR: In this paper, an electric field E applied to the bilayer produces a mechanical deformation in the piezoelectric, resulting in a frequency δ f or magnetic field shift (δ H) in the ferromagnetic resonance (FMR) absorption spectra.
Abstract: Studies on (i) microwave magnetoelectric (ME) interactions in ferrite-piezoelectric bilayers and (ii) electric field tunable ME signal processing devices are discussed. An electric field E applied to the bilayer produces a mechanical deformation in the piezoelectric, resulting in a frequency (δ f) or magnetic field shift (δ H) in the ferromagnetic resonance (FMR) absorption spectra for the ferrite. Bilayers of single crystal yttrium iron garnet (YIG) and lead zirconium niobate-lead titanate (PMN-PT) were studied. The strength of ME coupling A = δ H/E has been measured from FMR absorption profiles at 1–10 GHz for E = 0–10 kV/cm. Variation in δ f or δ H with E is found to be linear. A decrease in the ME coefficient is measured as the thickness of YIG film is increased. The fabrication and characterization of electric field tunable YIG/PMN-PT resonators are discussed.
54 citations
TL;DR: A detailed account of all salient aspects of Fused Deposition of Ceramics (FDC), two major technologies pioneered at Rutgers University, are discussed in this article, using connectivity as the unifying central concept.
Abstract: Piezoelectric ceramic-polymer composites have been conceptualized, prototyped, fabricated by rapid prototyping in order to surpass those fabricated with traditional processing methods in novelty as well as performance. Rapid prototyping offers unmatched design and fabrication flexibility in achieving structural complexity and hierarchy in developing piezoelectric composites. A detailed account of all salient aspects of Fused Deposition of Ceramics (FDC) and Fused Deposition of Multi-Materials (FDMM), two major technologies pioneered at Rutgers University, are discussed. Structure-processing-property relations are elaborated on using connectivity as the unifying central concept. Examples of novel piezoelectric ceramic-polymer composites fabricated using FDC and FDMM are given, and pertinent electromechanical properties are discussed. Pending challenges in this line of research are also elaborated on.
53 citations
TL;DR: In this article, the formation of the nanoscale domain structure in the surface layer as a result of pulsed UV laser irradiation has been studied experimentally in congruent single crystalline lithium niobate LiNbO3.
Abstract: Formation of the nanoscale domain structure in the surface layer as a result of pulsed UV laser irradiation has been studied experimentally in congruent single crystalline lithium niobate LiNbO3. The self-assembled structures have been classified and statistically analyzed. The structure is formed by growth, turning, and branching of domain rays strictly oriented along three Y+ directions. High-resolution microscopy shows that the rays represent the chains of individual needle-like nano-domains. The results of computer simulation of the domain structure formation using experimentally revealed rules are in good agreement with the experimental ones.
52 citations
TL;DR: In this paper, temperature dependence of mechanical strain connected with polarisation change in the paraelectric phase has been investigated for the BaTiO3 and PbZrO3 single crystals.
Abstract: Order-disorder mechanism is a part of phase transition nature in the ABO3 perovskites. It is related with the existence of polar regions, which dynamics in the electric field determines the dielectric response near T c. Temperature dependence of mechanical strain connected with polarisation change in the paraelectric phase has been investigated for the BaTiO3 and PbZrO3 single crystals. Existence of polar regions influences the electrostrictive properties and induces the piezoelectric effect in the paraelectric phase. A non-linear temperature dependence of the electrostrictive coupling between the macroscopic strain and macroscopic polarisation has been found above T c.
50 citations
TL;DR: In this paper, the shape of isolated domains produced by application of the uniform external electric field in different experimental conditions were investigated experimentally in single crystalline lithium niobate LiNbO3 and lithium tantalate LiTaO3.
Abstract: The shapes of isolated domains produced by application of the uniform external electric field in different experimental conditions were investigated experimentally in single crystalline lithium niobate LiNbO3 and lithium tantalate LiTaO3. The study of the domain kinetics by computer simulation and experimentally by polarization reversal of the model structure using two-dimensional regular electrode pattern confirms applicability of the kinetic approach to explanation of the experimentally observed evolution of the domain shape and geometry of the domain structure. It has been shown that the fast domain walls strictly oriented along X directions appear after domain merging.
49 citations
TL;DR: In this paper, a qualitative model for intergranular and transgranular mechanisms was proposed for both intrinsic and extrinsic failure mechanisms in barium titanate ceramics.
Abstract: Electrical breakdown phenomena of barium titanate ceramic were studied. Sintered ceramic samples made from high purity BaTiO 3 powders with varying particle sizes were obtained by heat treatment in the range of 1280∼1400°C. The resulting average grain size value changed from 1.3 μ m to over 40 μ m. After applying gold electrodes, electrical breakdown test was performed at two different temperatures, i.e. room temperature and 150°C, for samples immersed in silicone oil bath using 60 kV dc power supply with voltage rate of 500 V/s. As a consequence, both intrinsic and extrinsic failure mechanisms were identified and commonly occurred in these materials. Effects of sample thickness and grain size on breakdown strength are discussed in some details. Crystalline state, i.e. either ferroelectric tetragonal phase or paraelectric cubic phase, showed great influence on intrinsic breakdown mode. A qualitative model for intergranular and transgranular mechanisms is proposed.
TL;DR: In this article, the feasibility of utilizing piezoelectric ultrasonic motors and fiber matrix composites as an alternative to electromagnetics was demonstrated. But, the results are very promising and clearly demonstrate the promise of piezelectric technology.
Abstract: Electromagnetic actuators have been commonly deployed in robotics technology for obtaining expressions and other motion. However, the current technology is unable to meet the requirement of space limitation and at the same time provide high displacement and force (22–25 mm and force 2–7 N). The loss of space due to bulky motors prohibits the possibility of installing processing and control cards inside the skull of humanoid robot which is required to realize a smart expressive face. Our study shows the feasibility of utilizing piezoelectric ultrasonic motors and fiber matrix composites as an alternative to electromagnetics. The results are very promising and clearly demonstrate the promise of piezoelectric technology. A sample skin was developed from artificial room temperature vulcanized silicone material with piezoelectric unimorphs embedded inside it. For actuation, ultrasonic motors were implemented to drive anchor points of our humanoid robot-Albert to demonstrate facial expressions like opening and ...
TL;DR: In this article, a summary of recent developments in ferroelectric nanotubes, nanowires and nanodots, their electrical characterization and related theories of their structures, including the possibility of toroidal ordering is presented.
Abstract: A summary is presented of recent developments in ferroelectric nanotubes, nanowires and nanodots, their electrical characterization and related theories of their structures, including the possibility of toroidal ordering Also summarized is recent work on ultra-thin single crystals and a status report on thin films, particularly in [3D] configurations for DRAM or FRAM trenched capacitors
TL;DR: In this article, the softness of lead zirconate titanate ceramics (PZTs) is explained by electron exchange between oxygen and lead vacancies owing to the presence of these defects in every doped PZT.
Abstract: In the last two decades, Eyraud tried to interpret the soft characteristics in lead zirconate titanate ceramics (PZT) by an electron transfer between constitutive ions and/or dopants such as Ti3+/4+ or Fe2+/3+. These electron transfers are supposed to minimize the space charges (ρ p ) existing at the domain walls interface due to polarization divergences (ρ p = −div ), making the domain wall movement easier (soft PZTs). Recently, the Eyraud's model has been refined and the softening mechanism is now explained by electron exchange between oxygen and lead vacancies owing to the presence of these defects in every doped PZT. Based on the analogy with BaTiO3, the proposed correction of the model is justified using the energy levels of barium and oxygen vacancies given by Daniels and Hardtl. It is supposed that the material will exhibit soft properties if acceptor and donor sites are associated with neighbouring energy levels allowing direct electron tranfer between each other, without contributing to electron ...
TL;DR: In this paper, the spontaneous polarization (Ps) has been measured by the triangular wave method and the tilt angle has been determined by polarizing microscopy, and the relationship between the Ps and molecular structure has been investigated by the MO calculations.
Abstract: We have prepared new all-organic ferroelectric liquid crystalline materials containing a polar and dichiral cyclic-nitroxide unit within the rigid core. These compounds show distinct ferroelectricity in SmC* phases. The spontaneous polarization (Ps) has been measured by the triangular wave method and the tilt angle has been determined by polarizing microscopy. The relationship between the Ps and the molecular structure has been investigated by the MO calculations. The tilt angles, which are estimated from the layer distances of the SmC* phases determined by X-ray diffraction data and the molecular lengths calculated by the MO calculations, are consistent with those by polarizing microscopy.
TL;DR: In this article, the interplay between the various patterns of structural instability that are related to the electromechanical coupling in ferroelectric perovskites is discussed using results of density functional based first principles calculations.
Abstract: The interplay between the various patterns of structural instability that are related to the electromechanical coupling in ferroelectric perovskites is discussed using results of density functional based first principles calculations. We focus on two main issues: (1) the competition between tetragonal and rhombohedral ferroelectric states in A-site driven (tolerance factor, t < 1) perovskites, and (2) the competition of ferroelectricity and antiferroelectric octahedral rotation. The role of Pb is reviewed in terms of cross gap hybridization of Pb 6p states with O 2p orbitals, and an alternate mechanism for reducing the tendency towards tilt instabilities is discussed.
TL;DR: In this article, the effects of grain orientation for some bismuth layer-structured ferroelectrics (BLSF) systems such as Bi 4 Ti 3−xMxO 12 [BITN-x] or [BITV-x], for M = Nb or V (0 ≦ x ≦ 0.2), Srm−3+xBi 3− x Tim - xTaxO 3 m +3 [SBTTm(x)] (m = 2, x = 1∼2; m = 3, x= 0 ∼
Abstract: The effects of grain orientation for some bismuth layer-structured ferroelectrics (BLSF) systems such as Bi 4 Ti 3−xMxO 12 [BITN-x] or [BITV-x] for M = Nb or V (0 ≦ x ≦ 0.2), Srm−3+xBi 3− x Tim - xTaxO 3 m +3 [SBTTm(x)] (m = 2, x = 1∼2; m = 3, x = 0 ∼ 2), and Sr 2(1− x)Ca 2xBi 4 Ti 5 O 18 [SCBT-x] (0 ≦ x ≦ 1) on electrical properties were studied by the hot-forged (HF) method, comparing them with ordinarily fired (OF) non-oriented ones. The electromechanical coupling factors, k 33 , of BITN-0.08 and BITV-0.02 ceramics were 0.20 and 0.25 for OF samples, and were enhanced to 0.39 and 0.38 for the HF ones. The k 33 and piezoelectric constant, d 33 of the HF SBTT3 (0.3) ceramic were relatively high of k 33 = 0.37 and d 33 = 45.3 pC/N, respectively. The mechanical quality factor, Qm, of the SBTT2 (1.25) ceramic was high of 13500. The k 33 and the d 33 of the HF SCBT-0 were relatively higher values of 0.29 and 51 pC/N, respectively. Temperature coefficients of the resonance frequency, TC-f, in the (33) mode of ...
TL;DR: The homologous series of (S)-4″[6-(alkanoyloxy)hexyl-1-oxy]-4-(1-metylheptyloxycarbonyl)terphenyl, (S-4″ [6-(perfluoroalkaneyloxy),hexyl 1-oxy], 4-(1]-hexyl 2,3-difluoro-4-( 1-metelhexyloxy carbonyl), terphenyl and (S]-4″hexyl 3,oxy]-2,3dif
Abstract: The homologous series of (S)-4″[6-(alkanoyloxy)hexyl-1-oxy]-4-(1-metylheptyloxycarbonyl)terphenyl, (S)-4″[6-(perfluoroalkanoyloxy)hexyl-1-oxy]-4-(1-metylheptyloxycarbonyl)terphenyl and (S)-4″[6-(perfluoroalkanoyloxy)hexyl-1-oxy]-2,3-difluoro-4-(1-metylheptyloxycarbonyl)terphenyls have been recently synthesised. Their synthesis and mesomorphic properties were described. Liquid crystal phases were determined by thermomicroscopic and microcalorimetric measurements, and confirmed using the miscibility method. Temperatures and enthalpies of phase transitions have been measured.
TL;DR: In this article, the dielectric permittivity as a function of temperature at frequencies from 10−2 to 105 Hz is studied and parameterized in the perovskite Ba(Ti0.675Zr0.325)O3 ceramics.
Abstract: The dielectric permittivity as a function of temperature at frequencies from 10−2 to 105 Hz is studied and parameterized in the perovskite Ba(Ti0.675Zr0.325)O3 ceramics. The features characteristic of relaxor ferroelectrics are found, namely, the Lorenz-type temperature dependence at high-temperature slope of the real permittivity peak, the Curie-Weiss law observed at temperatures much higher than the temperature of the peak, the Vogel–Fulcher scaling of the temperature/frequency dependencies of the permittivity. However, scaling characteristics differ from those in classical complex perovskite relaxors suggesting different origin of dielectric relaxation.
TL;DR: In this article, the effects of compressive pre-stress on the dielectric properties of normal and relaxor ferroelectric ceramic composites in PZT and PMN-PZT systems were investigated.
Abstract: Effects of an uniaxial compressive pre-stress on the dielectric properties of normal and relaxor ferroelectric ceramic composites in BT-PZT and PMN-PZT systems are investigated. The dielectric properties are observed under the compressive pre-stress levels up to 15 and 5 MPa for BT-PZT and PMN-PZT, respectively, using a uniaxial compressometer. Both the dielectric constant and the dielectric loss tangent of the BT-PZT ceramics increase significantly with increasing applied stress. Larger changes in the dielectric properties with the applied stress are observed in the PZT-rich compositions. For PMN-PZT ceramics, the dielectric constant of the PZT-rich compositions increases slightly, while that of the PMN-rich compositions decreases with increasing applied stress. On the other hand, changes in the dielectric loss tangent with stress are found to be compositional independent. The experimental results are explained with the domain wall motion and de-aging mechanisms from the application of the compressive pr...
TL;DR: In this article, polycrystalline hexagonal Yttrium Manganites (YMnO 3 ) were prepared by solid-state route and X-ray studies revealed the formation of homogenous and single phase material in hexagonal structure.
Abstract: Polycrystalline hexagonal Yttrium Manganites (YMnO 3 ) were prepared by solid-state route. X-ray studies revealed the formation of homogenous and single phase material in hexagonal structure. Dielectric, impedance, electrical, magnetic and magnetoelectric measurements were performed on the YMnO 3 ceramics. Dielectric and impedance studies show relaxations near 200°C. Complex spectroscopic analysis, in the temperature range of 30–300°C from 1 kHz to 1 MHz, showed non-Debye relaxations. Ac and dc electrical measurements were extracted to understand the transport mechanism: Ac conductivity data is found to obey ‘Universal’ power law with exponent 0.8. Low temperature magnetization measurements were performed to understand the magnetic nature of the sample. Room temperature magnetoelectric (ME) measurements were also performed and corroborated with the magnetization data.
TL;DR: In this paper, a polymer network formed by in-situ photopolymerization of a small concentration of a commercial reactive monomer dissolved in the OAFLC was introduced to reduce the time for relaxation from the synclinic to the anticlinic state after switching off the field down to about 3 milliseconds at room temperature.
Abstract: Horizontally surface-stabilized orthoconic antiferroelectric liquid crystals (OAFLCs) provide excellent contrast electrooptic switching. However, in very thin cells the bulk relaxation to the anticlinic state tends to be slow because the synclinic state is upheld by the surfaces. In cells thin enough to accomplish a surface-stabilized state of today's short-pitch OAFLC mixtures, the field-induced synclinic (ferroelectric) states often become metastable making the corresponding bright electrooptic state prevail for long times after the electric field is switched off. Fast relaxation is then achieved by specially designed waveforms. By introducing a polymer network formed by in-situ photopolymerization of a small concentration of a commercial reactive monomer dissolved in the OAFLC, we have succeded to drastically reduce the time for relaxation from the synclinic to the anticlinic state after switching off the field down to about 3 milliseconds at room temperature, without the use of any tailored electronic...
TL;DR: In this paper, the authors used first-principles linear response calculations and molecular dynamics to study the relaxor ferroelectric Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-x PT).
Abstract: We have used first-principles linear response calculations and molecular dynamics to study the relaxor ferroelectric Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 (PMN-x PT). First-principles calculations for ordered PMN show a low-symmetry monoclinic ground state. A new set of phase transitions to lower symmetry rhombohedral and monoclinic structures is predicted for PT at high pressures, showing predicted piezoelectric response as high as is seen in the giant coupling relaxor ferroelectrics. We have developed a transferable shell-model potential for PMN-x PT by fitting to first-principles data. The potential qualitatively reproduces the compositional phase diagram for PMN-x PT. A new exchange-correlation potential, which gives excellent predictions for ferroelectric materials, is discussed.
TL;DR: In this article, the effects of strontium substitution, alumina addition and calcination temperature on phase development and the microwave dielectric properties of BSSmT ceramics prepared by the conventional mixed oxide process with the nominal composition, (Ba1− x Srx)2Sm2Ti9O23 (x ≤ 0.07) were investigated.
Abstract: The effects of strontium substitution, alumina addition and calcination temperature on the phase development and the microwave dielectric properties of BSSmT ceramics prepared by the conventional mixed oxide process with the nominal composition, (Ba1− x Srx)2Sm2Ti9O23 (x ≤ 0.07) were investigated. The phases synthesized upon calcination or sintering were analyzed by X-ray diffraction. It was found that the calcined powders were composed of (Ba,Sr)Sm2Ti4O12, Sm2Ti2O7 and (Ba,Sr)Ti4O9 phases, which converted to (Ba,Sr)Sm2Ti4O12 and (Ba,Sr)2Ti9O20 phases after pellets were sintered at the temperature from 1300 to 1350°C. Relative permittivity (ϵ r ) and the temperature coefficient of resonant frequency (τ f ) values were not much affected by the calcination temperature and Sr substitution, while the quality factor (Q·f) value was greatly influenced. It was also found that both strontium substitution for barium ions and alumina addition helped the formation of Ba2Ti9O20 secondary phase instead of BaTi4O9 seco...
TL;DR: In this article, the photoinduced nonlinear optics effects in the TEA-CoCl 2 Br 2 nanocrystallites incorporated into the photopolymer olygoetheracrylate matrices were investigated.
Abstract: The photoinduced non-linear optics effects in the TEA-CoCl 2 Br 2 nanocrystallites incorporated into the photopolymer olygoetheracrylate matrices were investigated. The temperature dependence of the photoinduced second harmonic generation demonstrates a remarkable dependence on temperature near the phase transitions. It was shown substantial changes of the photoinduced nonlinear optics effects with decreasing of the nanocrystallite sizes confirmed by independent absorption measurements. Comparison with dielectric measurements was done.
TL;DR: In this article, a tetragonal/orthorhombic morphotropic phase boundary (MPB) is found around x∼ 0.05, where the piezoelectric properties were enhanced.
Abstract: To elucidate mechanisms responsible for the enhanced piezoelectric properties in the potassium-sodium niobate-based solid solutions, phase diagram of the (1 − x) (Na0.5K0.5)NbO3-xATiO3 (A = Sr, Ba, and Pb) systems has been established according to the dielectric constant measurement and the crystal structure analysis results. A tetragonal/orthorhombic morphotropic phase boundary (MPB) is found around x∼ 0.05, where the piezoelectric properties were enhanced. Rietveld refinements show that the tetragonal/orthorhombic MPB is the same as that found in the lead zinc niobate-lead titanate system.
TL;DR: In this article, the authors examined the relationship between the Rayleigh's law and the complex dielectric constant notation used widely in the scientific and engineering community and showed that a modified complex notation can describe the field dependent Dielectric response w...
Abstract: Besides the high electrostriction in the relaxor P(VDF-TrFE-CFE) terpolymers, the high dielectric constant (> 50) and high breakdown field lead to a high electric energy density (∼10 J/cm3), which is attractive for the high efficiency charge storage capacitors. This paper presents charging and discharging behavior, as well as the discharged energy density as a function of the field. The field dependence of the polarization response and the polarization saturation at very high field result in a nearly linear increase of the discharged energy density with field. For the field dependent polarization response in the low to medium field range, Rayleigh's law has been introduced in the past to describe the field dependent behavior (with loss) in this field range. We examine the relationship between the Rayleigh's law and the complex dielectric constant notation used widely in the scientific and engineering community and show that a modified complex notation can describe the field dependent dielectric response w...
TL;DR: In this article, ultrasonic velocity and attenuation anomalies were observed near phase transitions (PT) in CuInP2(S,Se)6 semiconductor crystals, where S was partially substituted by Se.
Abstract: The ultrasonic velocity and attenuation anomalies were observed near phase transitions (PT) in CuInP2(S,Se)6 semiconductor crystals, where S was partially substituted by Se. It was shown that, crystals became piezoelectric not only in low temperatures below PT in ferroelectric phase but also at room temperature, which is far above the phase transition and under DC bias electric field, the electrostriction induced piezoelectricity appears. The anomalies of ultrasonic velocity, attenuation, second harmonic, and acoustoelectric voltage were also observed near the phase transitions in Cu 6 PS 5 I single crystals. These crystals belong to the polar symmetry group 3m at room temperature and exhibit a ferroelastic phase transition at 270 K.
TL;DR: In this article, the nanoscale electromechanical properties of Pb-based perovskites that are currently the main candidates for piezoelectric applications are investigated by Piezoresponse Force Microscopy (PFM).
Abstract: In this work, the nanoscale electromechanical properties of Pb-based perovskites that are currently the main candidates for piezoelectric applications are investigated by Piezoresponse Force Microscopy (PFM). Local response is compared with that studied via conventional technique. The effect of local polarization switching by mechanical force is demonstrated. This effect may limit the functionality of the films in piezoelectric applications. Local piezoelectric nonlinearity, as well as the nanoscale degradation are also studied by PFM. These measurements demonstrate that the defects may act as pinning centers for domain walls and thus influence nanoscale properties. Finally, local properties of ferroelectric relaxors are presented.
TL;DR: In this paper, the interactions between different kinds of proton exchange processes that may be used to create waveguides in congruent LiNbO 3 on the nonlinear properties of the crystal are discussed.
Abstract: In this paper we will start by presenting the interactions between the different kinds of proton exchange processes that may be used to create waveguides in congruent LiNbO 3 on the nonlinear properties of the crystal. We will then discuss the issues related to the interactions of the proton exchange processes with the electric field poling process. These observations are then used to choose the best protocol to create periodically poled waveguides in congruent LiNbO 3 .